Skin diving enthusiast Joseph Mielnicki, of Solvay, this week showed me a video of one he took recently while diving with others on a National Aquatics outing just off the western shoreline of Skaneateles Lake near the southern end.

"It was a little smaller than a 50-cent piece," he said.

Chris Legard, the Lake Ontario unit leader for the state Department of Environmental Conservation, said due to their size and other factors, freshwater jellyfish are often not spotted in the water. He said he's never seen one as big as the one Mielnicki videotaped.

One thing is for certain, Legard said. They're no danger to people.

Although their stings can paralyze small invertebrates and small fish, their stingers (nematocysts) are too small to penetrate human skin. These small jellyfish range in size from 5 to 25 mm. in diameter and are translucent with a whitish or greenish tinge.

Where'd they come from?

The U.S. Geological Survey lists the freshwater jellyfish (Craspedacusta sowerbyi) as a "nonindigenous aquatic species." They are indigenous to the Yangtze River valley in China.

How'd they get here?

It's unclear. They were "probably transported with ornamental aquatic plants, especially the water hyacinth from its native region of China. They were then possibly moved around accidentally through the stocking of fish and aquatic plants, or by birds, the U.S.G.S. website notes.

Excluding the colder states of Alaska, Montana, North and South Dakota and Wyoming, freshwater jellyfish have been recorded throughout the United States. They are most common in the eastern temperate states.

As for the Great Lakes region, they were first discovered in the Huron River near Ann Arbor, Mich. in 1933, and in Lake Erie shortly after. They have since been reported in Illinois, Indiana, Michigan, Minnesota, New York, Ohio, Pennsylvania and Wisconsin.

The ecological impact of freshwater jellyfish in this country is unclear, according to the the U.S.G.S. They are "opportunistic feeders," feasting on small organisms that come within their reach - particularly certain types of zooplanketon. They have been observed in laboratory situations eating fish eggs and fish larvae, but it's felt that doesn't happen to a large extent in nature. Crayfish "are considered their "only important predator."

Freshwater jellyfish are able to reproduce both sexually and asexually. Populations of freshwater jellyfish are frequently all male or all female, making sexual reproduction rare, the U.S.G.S. said. Read more about this unique, aquatic creature.